


History Lesson

by damsevendemigods



Series: *Young Justice/Arrowverse Crossover [5]
Category: Arrow (TV 2012), DC's Legends of Tomorrow (TV), Supergirl (TV 2015), The Flash (TV 2014), Young Justice (Cartoon)
Genre: And I'm basically writing another timeline, Basically, Kid Flash knows too much, Young Justice learns about everything from the Justice Society to the Speed Force, but anyways
Language: English
Status: In-Progress
Published: 2017-02-28
Updated: 2017-03-08
Packaged: 2018-09-27 09:22:17
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 2,004
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9997091
Author URL: https://archiveofourown.org/users/damsevendemigods/pseuds/damsevendemigods
Summary: After returning from a mission that ended them on another version of Earth, Young Justice returns to Mount Justice to find out that the Legion of Doom has become a known threat to the Justice League. The League tells the Team that they can't get involved. They aren't happy, but while benched, Wally decides to take this chance to catch the team up on who exactly the Legion is, why they were in what seemed like another dimension, and how everything got to be this way.





	1. Chapter 1

**Author's Note:**

> So! This popped into my head and technically it shouldn't be the next story in line, but I'm writing it anyway.
> 
> I was going to write a story about the team going to Kara's earth, but I decided to just mention that event happening in here- maybe one day I'll actually write it, but I had more ideas for this and I actually want to write this more so I am. 
> 
> Yeah, so don't question some stuff that happens here. I really wanna get used to the world I'm writing this in, and this is a good way for me to do that. Also, I feel like it clarifies some events that happened. I mention pretty much all of this stuff, and base it off of things that are in my Timeline story I wrote. You can find that if you want to read it (I recommend doing it!) on my account. 
> 
> This story is gonna have two (or more? Depends, really) chapters because I can. 
> 
> Sorry for grammatical errors/spelling errors. I tried my best but iPhones kinda suck when it comes to that and autocorrect screwed me over. I edited it, but sometimes I missed some stuff. Sorry!
> 
> I think that's all. Thanks for all your support on my other stories, guys. I really appreciate it! :)
> 
> Hope you enjoy. 
> 
> ~ Etta

Wally had a headache. Okay, not really - speedsters don't get headaches. 

But he figured that after all this, if he was able to get headaches, he would have one.

After everything he'd been through on that last mission, he thought things couldn't get more complicated. He was wrong. Very wrong.

Apparently, during the time they were gone, the Legion of Doom had decided it would be a great idea to piss off the Justice League. Wally's life just kept getting more and more complicated.

First, about a month back Thea Queen had shown up in 2011, when she was supposed to be on the Waverider with the Legends, and they'd had to "rescue" her from the League of Shadows after her father, Malcolm Merlyn, had ditched her there. 

Then a few weeks ago, he, Barry, Caitlin, Cisco, Julian, and HR had gone away for a week - just a week! - on a emergency trip to Earth Thirty-eight, to help Kara fight off some Dominators of her own. It turned out that Barry had actually forgotten to let the League know that he and Kid Flash were going to be off the grid for a while, and the league thought they went missing. 

Because of that, Young Justice had been tasked with a mission to STAR Labs, because apparently Jesse wasn't the best at keeping STAR Labs a secret. That mess ended with Jesse getting a lecture from Barry, and (Wally assumed) with Barry getting a lecture from Batman and the rest of the JL on keeping secrets.

Then, a few days ago they had been sent on a mission to check out these sources of some kind of energy or magic on Long Island. The source of that ended up being Klarion, who had thrown Wally and the team through a portal of some kind. 

Turns out the portal was a breach, and they ended up back where Wally had just been: Earth Thirty-eight. Supergirl's earth. Just his luck.

Wally had wanted to just try to find a way back to their earth, but Aqualad and the rest of the team had been very vocal about wanting to find Klarion, because they were convinced he was on that earth with them. It took them three days to find the guy, even with Zatanna using her magic to try to find him. 

However, when they went to get him, there was someone there already, and when he saw them show up, Klarion disappeared through one of his weird portal things right before the girl's heat vision hit him. 

Kara was happy to see him. Wally wasn't as happy to see her, since it meant explaining how her knew her to his friends (which he narrowly avoided, thanks to Kara not being dumb and remembering that for the most part, the multiverse was supposed to be kept a secret).

Eventually she was able to get them home, using the device Cisco had given her back when the Dominators invaded his earth. Of course, when they get back, they found out three days had passed there as well. And things weren't great back at Mount Justice.

When they got back, they didn't know what to expect, but it wasn't for Batman to lecture them for about ten minutes, and then get a call that forced him to leave the mountain and head up to the Watchtower.

When Batman came back, he brought the team's mentors along, and that's when they were told about the Legion of Doom.

When their mentors had shown up to tell them, they listened, but the team was still confused about what had happened on their last mission, when they went to another earth, and they wanted answers. Batman refused to tell them anything, but before he left, Flash turned to Wally and said, "Green Arrow, the others, and I told the league about everything; now it's your turn. Good luck." Flash smirked at his nephew, then sped off to follow the others.

And now here Wally was. He took a deep breath as his friend turned toward him, confused. But Wally knew what he had to do. 

"All right," he said. "Someone get me a whiteboard and a marker. It's time for a history lesson." 

_________________________________

I'll try to get the second part of this out as soon as possible. 

Hope you enjoyed. <3

~ Etta


	2. The Multiverse

**Summary for the Chapter:**

> Wally starts to explain stuff to his friends, and the Multiverse is still confusing.

**Notes for the Chapter:**

> Sorry it took so long for me to update this. Part of the reason why was that I was swamped with afterschool things last week, but it was mostly that I didn't have the motivation to write for a little bit. That happens sometimes, so even though I want to update once every week, I might not. I'm trying though. 
> 
> This chapter was fun to write. Part of it was inspired by that scene in the first crossover of Flash and Supergirl, when Barry explains the Multiverse to Kara, James, and Winn. I love that episode so, so, SO much! God, I'm such a nerd.
> 
> Sorry if anyone seems OOC, too. I just tried to write it how I felt it would happen but I wanted to keep it flowing with the others talking or interrupting Wally. And the ending is abrupt because I just wanted to cut it off there, but I didn't know how. WRITING IS HARD OKAY
> 
> If you guys have ideas or anything of where I should go next with this, I'd love to hear it. I know it sounds cliche but I really do love hearing what you guys think. It makes me smile when I get comments on this, so thanks. :)
> 
> Hope you enjoy this. 
> 
> ~ Etta <3

"So! Yeah! Uhh, where should I start?" "I don't know. Maybe at the beginning like any other person would, Baywatch?" Artemis said, laughing at her boyfriend. 

"Right. Okay, so, let's see... okay. So I think you guys have heard of the JSA, right? The Justice Society of America? Well, they got started way back in 1939 when World War Two started in Europe. The JSA lasted until the end of the sixties, but even though they were superheroes, they didn't fight crime all publicly like we do now- they dealt with things in secret, and they worked more with the Government. They're kinda like the first Justice League-" Wally started explaining, but was cut off by Robin. 

"Wally, we already know about the JSA. I thought you were gonna tell us something we don't know!" he said, crossing his arms. 

"I was going to, but you guys said from the beginning! Oh whatever. So anyways, I brought up the JSA because of Jay Garrick, who was kinda the first Flash but not really- it's complicated." "Why is it so complicated?" M'gann asked. Wally sighed. 'Here comes the crazy stuff,' he thought. 

"Well, it's like this. Jay Garrick was the first Flash on our earth. But he wasn't FROM our Earth. He's from a place we call Earth-3. Okay," he took a deep breath. "I know how that sounds. You're thinking I'm crazy. But I'm not- there's this thing called the multiverse. That's what happened when we went through that portal and ended up in a world that looked just like ours, but wasn't.

"The portals are actually called breaches. Whenever a breach opens, people can go through them and go to different versions of Earth. However, these breaches don't just open on their own randomly. Either someone with the power to open then has to do it, or in one particular case, multiple can be opened at once due to that singularity that opened... but that hasn't happened in years, and it won't happen again. So the-"

"Are you, Mr. I-Don't-Believe-In-Magic-Even-Though-It's-Right-In-Front-Of-My-Face, trying to tell us that the Multiverse Theory is real?" Zatanna said.

"Yeah, I am." He rolled his eyes., then picked up the marker and uncapped it, turning to his whiteboard. "Pay attention, because this gets complicated real fast." He drew five circles, and put these numbers in each: 1, 2, 3, 19, 38. "So, this," he pointed to the first circle, with a 1 in it, "is OUR Earth. Earth-1. Here, everything happened the way it did, more or less - I'll get into Flashpoint later though, because timelines suck and I want to save that for last - and now we're all where we are now. So, then there's Earth-2, and there things happened a little differently. But see, on Earth-2, pretty much all of us - more or less everyone on Earth - have doppelgängers there. People who look exactly like us, who are exact copies of us, well, most of us, and they just have different lives than us. So, on Earth-2 your dopplegängar could have had an event happen in their life there that didn't happen here and that may have caused something way different to happen. Um. It's hard to explain. Anyways, sometimes people here don't have dopplegängars there, and vice-versa. For example, my friend Jesse - she's the girl you met at STAR Labs - is from Earth-2, but she doesn't have a doppelgänger here because her mother and father here died before she could've been born, so she doesn't have a dopplegängar. And I'm also willing to bet Superboy doesn't have one on Earth-2, because I don't think Cadmus exists there, but he could have one on some other Earth because Cadmus could exist there. It depends on how the timeline goes on that earth." He paused, letting that sink in.

"Okay, but you never said exactly who those people are who can open those, what did you call them, breaches? How can they do it? And are these other Earths in different dimensions, or something? And how many other Earths are there?" Raquel asked. 

"Good questions. So, as far as we know, there's proof of at the very least fifty-two different Earths out there that we can contact or whatever. We haven't actually been to all fifty-two, but we know they exist. However, there could be infinite earths out there. Let's see. So, yeah, it's kinda like they're in different dimensions, but not really. Each Earth takes up the same spot in space, but every one of them vibrates at a different frequency. But see, if you're moving fast enough, it's possible to open a breach and travel there." 

The team gaped. "Are you trying to say that you can-" Kaldur started, cut off by Wally's response. "Yeah, I can. All speedsters can, if we run fast enough. Even ones from other Earths. But most of the time when we do, it's by accident. That's how Flash ended up on Earth-38, which is where we were, and why I knew what to do when we got there. I've met Supergirl before. She's a friend of ours." He smiled. He didn't get to see Kara much, but he loved going over to her universe and helping her out. "There's another meta who can open up breaches too. His name is Vibe, and his powers let him do that, along with some other stuff. He's a good friend of ours too. Some metas from other Earths have powers like ours, so they can travel through breaches easily too. The thing is though that when Vibe opens a breach, he can normally hold it open for as long as he wants, and multiple people can go through, no matter who they are, but when Speedsters do it, we travel through something called the Speed Force, which I'll get to explaining later, so it's really just us who does it."

"But neither of those ways you mentioned is how we got back here." Connor spoke up. "Huh?" Wally looked confused. "We got back because that girl, Supergirl, had some device that opened the breach to let us go back. What was that?" Conner narrowed his eyes. "Oh, yeah. I forgot about that." Artemis rolled her eyes and smiled. As smart as Wally was, he could be an idiot sometimes. Good thing she thought he was cute. 

"That device was something Ci-Vibe and Flash made. It enabled the user to open a breach on command to just Earth-1 and Earth-38 specifically. Vibe gave it to Supergirl after the first time she came over to our Earth, so that she could come over and go back whenever she needed to. It also works as a communicator between the two Earths. We have a few friends on Earth-2, Jesse and her dad, who have one of these as well." 

Wally looked around at his friends. They seemed really confused, and he didn't blame them. He still got confused about it sometimes. Thinking about things like the Speed Force, the Multiverse, time travel... it all gave him a headache. There was so much that the team didn't know, and for him to tell them, and he knew it'd take a while, so he said, "Guys, if you want to take a break we can. It's a lot to process, I know. If I was you, I'd be confused out of mind too." The team seemed glad to be able to get up for a bit. "I know, I'll make some snacks for us, and then we can come back and Wally can keep explaining!" M'gann suggested, with a smile on her face as always. "Thanks, Meg. That'd be great." Wally smiled.   
_________________________________


End file.
